1. Field of the Invention
The present invention relates to an interpolation method for color reproduction, particularly to a heterogeneity-projection hard-decision interpolation method for color reproduction.
2. Description of the Related Art
The digital camera uses a lens to project scenes onto a Charge Coupled Device (CCD), and the CCD transforms the scenes into digital image signals, and next, the digital image signals are processed by electronic circuits and then stored in a storage medium. The CCD cannot sense light colors but can only sense light intensity. Therefore, a color-separation filter needs to be arranged before the light-sensing element for a digital sampling. Generally, the color-separation filter uses the RGB (three primary colors) color model. The color components separately acquired by three CCD's are combined into a full-color image. In considering cost and volume, the digital camera usually uses only a single CCD. Each pixel only has the gray-level value of one of three primary colors, and the other two color elements are lost. Therefore, the result obtained by the CCD needs to be processed using an interpolation algorithm to reconstruct the missing color elements.
Generally, image interpolation methods may be classified into the fixed type and the non-fixed type. In the fixed type image interpolation method, the weight values of the neighboring pixels are fixed in reproducing the missing color element. The fixed type method lacks the edge detection capability; thus, the edges of the output image appear blurred, and the detailed texture cannot be recovered well. In the non-fixed type image interpolation method, the weight values of the neighboring pixels are unfixed in reproducing the missing color element. The non-fixed type method possesses the edge detection capability; thus, the edge blurs of the output image are greatly reduced in the horizontal and vertical directions. However, the detailed texture cannot be recovered well in the non-fixed type method either.
A Taiwan patent No. 00548956 proposed a “Color Interpolation Method For Digital Images”. However, such a conventional technology has color distortion in the rebuilt digital color images. Besides, the detailed texture cannot be well recovered either.
Accordingly, the present invention proposes a heterogeneity-projection hard-decision interpolation method for color reproduction, which can effectively interpolate the edges of digital images and can sensitively detect the passage of an edge and can thus effectively recover the details of texture.